1. Field of the Invention
The invention concerns a video recording/play-back head and, more particularly, a recording head comprising a protective layer against wear due to the magnetic recording tape. It especially concerns a method for making a head of this type as well as an apparatus used to implement this method.
2. Description of the Prior Art
At present, magnetic heads of the type used in domestic video sets (VHS) are subjected to friction from the tape which runs past at a speed of 5 ms.sup.-1. This produces wear of about 20 micrometers per 2000 hours of use on the substrate of the head and, hence, on the poles. There are at least two of these heads and they are mounted diametrically opposite to each other on a drum with a diameter of a few centimeters. The drum is machined with thin helicoidal grooves (of a depth of 200 micrometers) in order to exert suction on the surface of the tape and so that no film of air can prevent contact between the tape and the head. This drum, and especially the recorded grooves undergo erosion. This erosion produces waste material, such as metallic powder coming from the drum, which may form a powder which is abrasive with respect to the magnetic heads and aggravates the causes of wear in the magnetic heads.
Furthermore, the tape is subjected to a gap in the material, generally a gap between the drum, which is made of aluminium, and the magnetic heads which are made of ferrite. These gaps result in differences in adhesion which may give rise to more accentuated friction on the drum or on the magnetic heads.
Furthermore, the heads are placed in housings provided in the drum. These housings create eddies around the head, thus accentuating differences in adhesion.
The invention provides a solution to prevent the wearing out of the drum and the magnetic head and to eliminate differences in adhesion which may exist between the magnetic tape and the drum, on the one hand, and between the magnetic tape and the magnetic heads, on the other hand.